The present invention relates to a brake apparatus for a heavy vehicle which requires a large braking force for stopping. More particularly, this invention relates to an improvement in a disc braking apparatus of the type in which a plurality of stationary discs mounted axially movably in an axle housing and a plurality of rotary discs mounted axially movably along an axle shaft driven through a ring gear of a gear box are arranged alternatively to the stationary discs in an axle housing. The rotary discs are urged against the stationary discs respectively by pressure from an hydraulic piston provided in the same axle housing, to obtain a frictional braking force.
An assembling operation of the conventional braking apparatus of the type mentioned above is performed through three steps.
In order to describe these three steps and to clarify the improvement according to the present invention, reference is made to FIG. 2, showing a typical example of the conventional brake system for heavy vehicle such as a fork-lift truck shown in FIG. 1.
In FIG. 2, a piston holder 2 has an annular piston 9, to be mounted, and an axle housing 1 in which axially movably stationary discs 4 are mounted following separate preparation and then they are assembled in succession to a differential housing 17 by bolts 18. In this case, an axle shaft 3 having a spline structure onto which rotary discs 5 are mounted for axial movement, extends from the differential housing and is supported by bearings 12 fixed in the axle housing 1. That is, in the conventional brake apparatus, the stationary discs 4 and the rotary discs 5, both of which are disposed alternatively in the axle housing 1, and the hydraulic piston 9 for urging the stationary discs 4 against the rotary discs 5 are assembled simultaneously with an assembling operation of the axle housing 1 and the piston holder 2 to the differential housing 17.
As is well known, the assembly of the piston holder and axle housing to the differential housing is generally performed in one of the steps of a vehicle assembly line operation. It requires considerably skilled labour to perform the assembly of the brake system simultaneously with the assembly of the axle housing and the axle shaft within a given time during the line operation. Even given a sufficient level of skill, it is still difficult to perform the task, causing problems such as degraded preciseness of assembly, delays on the line, and the like to occur.